Biennials to Sow Now
Biennials are so useful in the garden as they flower in spring and early summer before the later summer-flowering annuals – and if you sow them now (in June and July) they should flower the following year. My top three biennials are honesty, foxgloves and wallflowers. Let’s start with wallflowers, which are the earliest to flower in spring. Cultivars of Erysimum cheiri are the ones to sow now for early spring displays. Grown in swathes of soft (or bold) colour, they provide the perfect foil for tulips, and their scented blooms are good for the vase too. ‘Giant Pink’ (shown above) has flowers that cluster up the stem in darker and lighter shades of pink, combining well with a dusky purple tulip like ‘Havran’ or even in a clash of colour with a deep orange tulip such as ‘Ballerina’. ‘Ruby Gem’, ‘Sunset Apricot’ and the curious ‘Plant World Lemon’ are also on my list to try.
My favourite honesty is Lunaria ‘Corfu Blue’ which is a more sophisticated form than the common magenta-pink honesty. It has beautiful purple-blue flowers (shown above) and forms a more substantial and bushy plant than the common magenta-pink Lunaria annua. In my garden this year large drifts of it was flowering as a backdrop to my tulips and it looked amazing for weeks. As the flowers fade they lose their intensity, some petals turning lilac-white, and then they quickly form large round seed pods that age to greeny-purple on the plant.
Forms of the common foxglove, Digitalis purpurea, can be sown now to flower next May and June. I love ‘Sutton’s Apricot’, which has soft, peachy-pink flowers on slightly curvy spires, and ‘Dalmatian White’, with dusky purple spotting inside its pure white blooms. Both are happiest in dappled or partial shade. Digitalis grandiflora, a perennial foxglove with pale buttery yellow flowers, can also be sown now. This comes back reliably year after year in my garden, is slightly later flowering than D. purpurea, and is more tolerant of full sun.
All these plants and more are featured in my book, The Flower Garden. Photographs above (and in the book) by Sabina Rüber.
How to sow biennials
All biennials can be sown directly into the ground or in seed trays. I tend to sow everything in seed trays first, and then plant out when they are big enough, but if you do this, you have to be committed to watering them throughout the summer (perhaps easier this year with all of us spending more time at home). Foxgloves and wallflowers have tiny seeds so it’s best to sow them into standard seed trays, sprinkling the seed on the surface of seed compost, and then covering with a very fine layer of more sieved compost or a layer of vermiculite. They will then need pricking out in five or six weeks’ time. Honesty on the other hand has large seeds that are best sown in modules or plugs, and can be planted directly into the ground from there without disturbing their roots. Once sown, soak the seed trays in a gravel tray and leave them outside in a protected place. The greenhouse is probably too hot at this time of year, but a cold frame would be good if you have one, or on an outdoor table so that they are raised up from the ground. Then keep the seedlings watered as they emerge and grow, potting on if necessary, and plant them out in their final growing positions in late summer, to carry on forming their leaves and root systems in the autumn.
Other biennials to sow now
Hesperis matronalis, sweet rocket; Dianthus barbatus, sweet William; Althea rosea, hollyhock; Anthriscus sylvestris ‘Ravenswing’; Matthiola incana, scented stocks.
Buy seeds from Chiltern Seeds, Higgledy Garden or Seedaholic.
